>I know that it could be different in Canada and in the U.S.A.
>
>Are there laws protecting by default the look & feel of an application or would I have to contact a lawyer to do it?

I sure hope not.

But, if there is I'd like this post to serve as my claim to right-click context menus, toolbars, horizontal rows on grids, borders around textboxes, 3-D shading in general, short-cut keys, the letter "E", and the general color scheme of gray/white/light-blue. <g> Don't worry, there's plenty of UI elements left for you to stake your flag.

On the serious side, Microsoft actually has done things similar to what you are asking about. The most recent (that I remember) was/is with the Microsoft Ribbon control (only approved vendors/implementations had the green light to implement a 3rd party ribbon control. I'm not a lawyer, nor do I play one on TV, but silly stuff like this is unenforceable. The best you can do is throw it in as part of the License/EULA and hope that, if your claim has some merrit, "good faith" will prevail, and your restriction will be respected by the targeted end-users and your competitors. I'd be interested in knowing whether there even is a modern UI look-n-feel in existence that couldn't be shown to have been derived or copied from prior-art.

As for any Look-N-Feel I may have ever created... feel free to go crazy and steal it all.